Red Sox starting pitcher Garrett Whitlock reacts as Toronto’s Brandon Belt rounds the bases after hitting a solo home run Sunday. Whitlock left the game after one inning with right elbow tightness. Frank Gunn/The Canadian Press via AP

On Monday the Boston Red Sox enjoyed their final day off before next week’s All-Star break, but it couldn’t have been very relaxing for manager Alex Cora and the front office.

Cora undoubtedly spent much of the day trying to figure out who is going to pitch in the six home games leading into the Midsummer Classic. As of Monday morning, we knew Brayan Bello was going to start Wednesday’s game against Texas.

That’s all we knew. James Paxton and Kutter Crawford should each get a start during the homestand, but the other three games are wide open after another starting pitcher went down over the weekend.

Garrett Whitlock, who had shown such promise as a starting pitcher before struggling in his last two starts, left Sunday’s game after one inning with right elbow tightness. Those are words that usually send a chill down the spine of any pitcher, often a precursor for more serious trouble ahead.

We don’t know the extent of Whitlock’s elbow issue. We do know he was on the injured list earlier this season with right elbow ulnar neuritis.

Amazingly, he was able to resume throwing just days after being placed on the IL. There was concern that he would have to undergo Tommy John surgery for the second time in his career. Luckily, he didn’t.

The Red Sox are hoping they are just as lucky this time around. Whitlock didn’t sound like he was feeling lucky after the game in Toronto.

“We’ll see what the doctors say about it,” Whitlock said to reporters Sunday. “I’ve just kind of been dealing with things, kind of like being stiff.”

Whitlock hinted that the issues had been going on before Sunday’s start. It’s hard to imagine he’s not headed for the IL. That would put four starters — more than half a rotation — on the shelf.

Chris Sale is on the 60-day IL with left shoulder inflammation. He was throwing at Fenway last week and said he was confident he’d be able to return soon after he is eligible in early August.

Corey Kluber is also on the IL, though he had already been demoted to the bullpen after struggling throughout the season.

Tanner Houck is recovering after undergoing surgery at Mass General to have plates installed around his cheekbone after he was hit in the face by a line drive off the bat of the Yankees’ Kyle Higashioka.

It was a scary moment, and the injury could’ve been much worse. Another scary moment came Saturday at Rogers Centre in Toronto when Kevin Kiermaier ripped a liner back up the middle. It deflected off Crawford, bounced back to home plate, where catcher Caleb Hamilton grabbed it and threw Kiermaier out at first.

The ball was traveling 101 mph when it hit Crawford, who seemed to get his glove up in time to deflect the ball. He returned to face three batters the next inning.

On Sunday, Nick Pivetta barely got out of the way of a George Springer line drive that whistled by his head at 104 mph. Pivetta threw himself to the ground and avoided injury. That would’ve been another devastating blow. The Red Sox will need Pivetta to either start or provide multi-inning relief this week as they take on the Rangers and the Oakland Athletics.

Boston pitchers clearly must feel like they are wearing a bull’s-eye. And there’s no doubt pitching will be the target of Red Sox President of Baseball Operations Chaim Bloom’s search for help with the trade deadline less than a month away.

Monday should’ve been a day for Red Sox fans to relax and enjoy one of the best weekends the team has had all season. A sweep of the Blue Jays in Toronto put Boston back above .500 and within 3 1/2 games of a playoff spot.

Yet most were worrying about the immediate future. A future that included “TBA” listed as the starting pitcher in five of the next six games.

Tom Caron is a studio host for the Red Sox broadcast on NESN.